In present-day dance culture which is characterised by modern electronic music, the occupation of the disc jockey (DJ) has experienced enormous technical developments. The work required of a DJ now includes the arranging of music titles to form a complete work (the set, the mix) with its own characteristic spectrum of excitement.
In the vinyl-disk DJ sector, the technique of scratching has become widely established. Scratching is a technique, wherein the sound material on the vinyl disk is used to produce rhythmic sound through a combined manual movement of the vinyl disk and a movement of a volume controller on the mixing desk (so-called fader). The great masters of scratching perform this action on two or even three record players simultaneously, which requires the dexterity of a good percussion player or pianist.
Increasingly, hardware manufacturers are advancing into the real-time effects sector with effect mixing desks. There are already DJ mixing desks, which provide sample units, with which portions of the audio signal can be re-used as a loop or a one-shot-sample. There are also CD players, which allow scratching on a CD using a large jog wheel.
However, no device or method is so far known, with which both the playback position of a digital audio signal and also the volume characteristic or other sound parameters of this signal can be automatically controlled in such a manner that, a rhythmically accurate, beat-synchronous “scratch effect” is produced from the audio material heard at precisely the same moment. This would indeed be desirable because, firstly, successful scratch effects would be reproducible and also transferable to other audio material; and secondly, because the DJ's attention can be released and his/her concentration increased in order to focus on other artistic aspects, such as the compilation of the music.